Sherlock Holmes and the Black Widow
by Gracie Holmes
Summary: Sherlock gets called in to solve a case at the New Avengers Facility in New York. A trip that ends up giving him more than just an intriguing impossible case. He meets a kindred spirit in the middle of the night. (Gift for Angie, Red on Pointe)


**Sherlock Holmes and the Black Widow** by Gracie Holmes

* * *

It was very, very early a mid-December morning and Sherlock Holmes was sitting on the ground in front of a large wall of windows, looking out over the dark fields that surrounded the New Avengers Facility in upstate New York. He'd not slept of course. Not yet at least, for his mind was elsewhere.

He was accustomed to working odd cases, since he did prefer the challenge over anything else. He was also used to being called for across the oceans and continents, whether missions or cases. He had an international reputation after all. He was the best.

Yesterday morning he'd been called in to consult for a very special and well known group of people.

And by called in, he meant there'd been a conversation with Mycroft and someone named Fury. Sherlock had kinda skipped that part, deleting all but the necessary information. Since he'd currently been case-less in London for going on a week, a mission to the States had been a welcome change.

John hadn't been able to join him. The good doctor had recently come down with the flu. With Mary and the baby around, he was in good hands, but he was also not feeling well enough for a trip to America. Not unexpected. Hardly the first time Sherlock had worked an abroad case alone.

But distractions. He dismissed the lack of John simply and moved on. He had a case to solve. The New Avengers Facility in rural New York had a mole and he'd been called in specifically. Sensitive information was leaking out of the facility on some terribly top secret biochemical work. There was just about two hundred people staffed at the New Avengers Facility, from the few Avengers, to scientific researchers, to the medical personal, military training, weapons research, to the trainers and janitors and anyone else there to keep the place running.

Anyone could be a suspect.

And there was a timeline, a deadline.

When the world's heroes ran out of options and needed an outsider, they went to Sherlock Holmes. Or so it seemed like this time around. The telepath couldn't tell who it was and options were limited, they needed someone from out of the facility itself to come and figure it out. It was a challenge he readily wanted to embark on.

Even Sherlock couldn't predict how this one would be more than just an interesting case.

His flight had landed only hours previous, he'd gotten a tour of the facility under the guise as a new hire for a job on the science team, biochemistry department. Twenty minutes in, he promptly escaped to do his own investigating.

Their mole was leaking scientific information to an outside source, someone who's unknown powers made it entirely difficult to pin either of them down. The Avengers hadn't been able to do it. But that didn't mean they weren't trying, so Sherlock was currently in competition to catch the perpetrator.

That fact was both good for the case and good for his ego.

He had a fairly good idea though, after his time in the lab. It was only a matter of time. But he had to sort through the obvious and the details. Which is what was currently keeping him awake.

He wasn't the only one. But, being lost in his head, he hadn't noticed he had a guest until she spoke.

"You're up late." A female voice called from somewhere behind him in the large open space.

Sherlock didn't turn around, he knew exactly who it was based on the barely noticeable lilt in her accent. Even if they hadn't met in person. He'd been given all the personality profiles and done his own research into 'the Avengers' already. His fingers tapped together in front of his chest. "Am I? Hadn't noticed."

He didn't see, but she did smirk. She spoke again. "Most people are up and about around 6am, at least Steve begins his prowls around then, 6:30 if he's sleeping in. You've got a while before others come asking questions like why the new hire is sitting alone away from the sleeping quarters."

"Couldn't sleep."

"Yeah?" Her voice was soft, the question not pushing an answer.

Sherlock was quiet, unintentionally so. And a few minutes when he reemerged from his mind, she was still there. He blinked, tilting his head as he caught her figure and splash of red hair near the windows in the dim light of the moon instead of behind him. "You're still here."

She turned her head, just enough for him to see her profile. "I didn't feel like sleeping either."

 _Nightmare._ The deduction was obvious. From her sweatpants, messy bun, and her hoodie, to the fact she had no less than three weapons on her person and was wandering the halls of the facility at half four in the morning. She wasn't on guard duty, nor was there any reason to be awake. PTSD was also something that was expected from someone with her history and current career, so the leap wasn't huge. John might have told him not to mention it, but he was himself, somethings never changed. "You had a nightmare."

She turned her face fully, her expression completely blank. And her one word response was just as impassive. Guarded. "Yes."

"Not just any nightmare. Not the kind that keeps you in bed and lets you sleep again, the kind you need to walk off." Sherlock continued. "Common for you, of course, to have the smaller ones. So it must have been bad. You probably rate or rank them, it's a common but effective technique."

"You're good." She said.

"I know."

"My turn." The redhead said. "You're not here for an interview and a new job. You're out here, alone. Your chemistry skills are superb, but you've lied about your name and your intentions. Anyone who pays attention to British news would know. Styling your hair differently and adding glasses may work for some people, and the scientists here, but not me. You're good. So I can honestly say, it's a pleasure meeting you, Sherlock Holmes."

His mouth twitched into a smirk. "And you as well, Agent Romanoff."

"Fury called you in, didn't he?"

"He called my brother, who recommended and contacted me, yes."

She paused, eyes turning back to what they could see out of the windows in the full moon. "No one else will know. I doubt anyone's as informed as I am. And most of the scientists here aren't looking for a detective."

"Consulting detective. Obviously, most of them have their noses in one computer screen or another." Sherlock said. "None of the know about the leak of information, aside from the mole, of course. I've got some fairly good ideas. Four, in total."

"Oh?"

Sherlock gave her an enigmatic look. "And you'll know when I pin it down to just one. You're still on the suspect list, low of course. But it's still a non-ruled out possibility. There's a theory that includes mind control. Another, imposters. And a couple more there's no need to mention yet."

"Wouldn't you be dead already if I was being mind controlled and knew exactly why you were here?"

Sherlock tilted his head just slightly in intellectual and personal curiosity. "I'd like to see you try, but that's a fair point."

"Of course it is."

"Still, if I want to talk about theories, I know where to find you. I'd rather not share until I have every last bit I can investigate mulled over. I appreciate the touch of the dramatic."

Natasha gave him her own look, not intimidated and nearly cheeky. "I'll take your word for it. I do expect a full report though, when you do find the suspect."

"Expect?"

"That is the word choice I used yes." Natasha said, turning fully around. She tilted her head. "After you solve this one, I'd like to see you, talk it over. I'll find you. Coffee?"

"Black, two sugars." He answered a moment later.

She winked at him, eyes otherwise bright in the dim light. "Deal."

* * *

In the end, it had only taken another read of personal files and a day of working alongside the suspects in the laboratory before he caught the mole. Sherlock worked diligently, on the case rather than the biochemistry work he was supposed to be doing. Observation and deduction and studying everyone's behavior pattern while he was among them, not just from a security camera.

Rather than a mole, Sherlock deduced that whoever was siphoning the information out was not willingly doing it. The slight change in manner of his current suspect, the lead of the project, was the biggest clue.

There were many possibilities; from a possession, to a duplicate, to a parasite that had infested and took over whenever it deemed necessary. The impossible was possible when they were dealing with the possibility of inhuman or alien life.

The perfect cover. The victim in this case was Dr Brianne Zamora, a biochemist from Arizona with a sunny smile and love of poetry. Sherlock had been watching for deductions, changes in behavior that couldn't be explained, a change of handwriting, the coffee mug left untouched. A day was ample time, but this one was tricky. And he wanted to be absolutely certain with as delicate a project as the one they were all working on.

Problem was, once the issue was close to being exposed, and Sherlock was closing in, the _being_ acted. The laboratory, with minimal staffing and guards too far away, wasn't ideal for an encounter. Sherlock wasn't exactly armed and ready for this. He was missing his blogger-doctor after all.

For some reason, the thing knew he was about to call for back up, knew that as he pulled out his phone to send a text, it's undercover and hidden operation was discovered. Likely telepathic to some extent, but the deduction wasn't in time. Dr Zamora's deep brown eyes flashed unnaturally bright green and suddenly there was a gun. "I knew something was off about you." It said, it's voice sinister as it walked towards him, gun pointed at his head. "My brothers and sisters will rise. You cannot stop it."

Before the shot went off there was a blur of red and black and Sherlock was pushed out of the way as Natasha Romanoff came to his rescue. The thing controlling the biochemist was very strong, but also susceptible to the gauntlets she wore on her wrists. The biochemist went down, but not before alarms started sounding in the laboratory and the entire facility.

Natasha got up from the ground and glanced over the unconscious woman, tapping her radio once as she stowed the gun. "Rogers, update….wonderful…It's down at the moment…yeah, electricity….stay in touch and don't one of them near you. Wouldn't want to put you on the ground too. And I need medical in Lab Four asap. Out."

She clicked the radio off and turned back to Sherlock, looking him over quickly. "There's more of them, Steve thinks about a half dozen or so that have taken over the communications room."

"They're telepathic to some extent. I'd say…what do you call it? Hive mind?" Sherlock spoke fast, shrugging out of the white lab coat he'd been wearing. After tossing it on the bench, he rolled up the sleeves of his dress shirt and ruffled his hair.

Natasha may have looked pleased, but not surprised, and she nodded. "Sounds plausible. Let's plan on there being more than just those seven and start a search. Steve's already on it."

"And the plan is to figure out who they are and take them down before they either get out, compromise the base, or hurt anyone else."

"Exactly." Natasha glanced once more at the unconscious body and headed towards the door. "You're coming with me."

Sherlock didn't argue with the blatant order, he knew when to let the experts take over. "I'm sure you know to utilize my abilities if it's necessary."

"Of course, I'm planning on taking advantage of you." She quipped. It was not a flirtation, and neither of them would take it as such. She took the lead as the walked down the hallway as quickly as possible.

She'd occasionally check up with Steve Rogers, who was running a similar hunting operation on the other side of the facility. And it was as they were making there was through the living quarters and common room areas that Sherlock's abilities would be coming in handy.

The _things_ were relatively unknown as to where they were from, what they wanted, and what they planned to do. There were too many unknowns. And an enemy that could hide in the body of an innocent who was none the wiser. It was a delicate situation that couldn't be allowed out of the base.

If he did say so himself, and he probably would, it was a good thing Sherlock Holmes was there to help. As they walked through the common areas, quick all seeing eyes scanned the groups of people. These 'brothers and sisters' were dangerous. Obviously so, it they've infected an unknown number of people. They could do some damage, not only to the people they were occupying but the facility itself and the secrets that would otherwise be compromised.

The things weren't working as hard to hide anymore, so behavioral patterns were different. People walking the wrong direction down the hall. People not jumping when a loud noise sounded. Access codes not entered properly. Natasha was going through them like a hot knife through butter. Jumping and attacking with her gauntlets. The four she'd taken down already remained unconscious on the ground. Clean up security crews were on the way.

But the alarm was raised, it was only a matter of time before those that were still around would get violent. Their next stop was the cafeteria, which had just about two dozen people interspersed among tables and chairs in the large mess hall. All looked a bit nervous in the face of alarms and moving security teams.

Sherlock put his hand on Natasha's arm to get her attention after a moment of studying the crowd. Once her eyes turned to him, he spoke in a hushed tone to point out. "Three people near the window…not talking to each other and no nervous tics. Woman in green cardigan, man in blue polo, man in navy suit and pink tie."

Later she'd teach him about her battle math, her own sort of observation and deductions she used to stay alive in the field. But there wasn't time for that now.

Natasha nodded but gunfire interrupted whatever she was going to say next as it erupted across the cafeteria. People screamed, trays were abandoned. Sherlock himself froze, but a small hand pushed him towards the door and out of the direct line of fire.

"Get out and don't get shot." Her voice was harsh and in his ear as she spoke into the microphone as well. "Rogers! Cafeteria, people down, don't need your help just thought you should know."

Sherlock didn't go out the door all the way, he stood by the entrance and waved people his way. Natasha, on the other hand, was in her element.

Red hair fanned out as she leapt forward. She propelled her body in a running start at the three possessed people. They had split up, two of them circling around her. Not a problem. She didn't reach for her own gun, hesitant to draw a weapon against civilians who were no more than victims stuck in their own bodies.

She approached the first man with her signature move, and down he went. She was on him with the gauntlets a moment later and his body jolted with the electricity. The next was the woman, who'd already fired several shots at Natasha, all missing their target. The Black Widow wasn't going to be stopped that easily.

Natasha flipped up and around, kicking out and dodging another bullet at the same time she disarmed the woman. She went down in a blur of green cardigan and black hair as electricity coursed through her body. The last man was reduced to a heap in a similar manner and soon three unconscious bodies were scattered on the floor.

Sherlock had been scanning the people who were fleeing the attack, trying to be sure that they were in fact human. He couldn't be sure. But he was fairly confident everyone was cleared.

When there was nothing to do but step out of the cafeteria himself, he didn't. He watched the scene play in front of him. And if he was being perfectly honest with himself, he was appreciating watching Natasha work. She was skilled, a quick thinker, and went through disarming the trio with a graceful beauty he couldn't quite describe with any other words.

He dismissed it as she came back over, all slowly calming breath and wind-swept wavy red hair. He stepped back and out the door so they could continue on towards the communication room. A second later he spoke. A honest appreciative compliment. "Excellent work."

"It usually is, I don't like being a disappointment." She quipped in return, glancing once more over her shoulder until they were out the hall.

Whether she'd been planning it or not, Sherlock had no idea. But one moment he was very casually walking, and the next moment Natasha's fingers were gripping the fabric of his shirt and pulling him closer to her. She gave him one moment to reconsider, green eyes bright and open and allowing him to deduce her intentions. He didn't stop her, and the next moment their lips met. Her grip loosened on his shirt and instead fingers carded through his mostly curly hair and her taut body was pressed up against him.

She took the lead, because he really wasn't accustomed to this type of interaction. It wasn't unpleasant, in fact, he was quite enjoying it. Surprisingly. And if he bothered to think about it. Her lips were soft, her touch was calculated.

When they finally broke apart there were deep ragged breaths, and neither of them moved from where she'd pressed him against the wall. He couldn't particularly figure out when that happened. Not that it mattered. Sherlock spoke first, "We were under attack weren't we?"

"Still are." Natasha replied, looking away from him and down the hall again. "My calculations were correct though…we've got a couple more minutes before Steve shows. The medical team shouldn't be too far behind." She turned back to him, scanning his features and then letting a small smirk grow on her red lips. "I just was curious."

"Hm." Sherlock made a noise of affirmation as footfalls hit their ears

Natasha switched right back to business, like she'd never left the mindset. And she let go of him with nothing but a careful smooth of his shirt. Pulling her weapon wasn't necessary because she quite obviously knew the footsteps belonged to Steve Rogers.

Steve gave him a once over, but turned his attention immediately to Natasha. "Maximoff's gotten into the communications room, she's got them all subdued."

"Good. Everyone else?" Natasha said, walking with him.

"We've already got Doctor Beckett working on figuring out what happened with Doctor Zamora. Everyone who was infected is being placed in solitary confinement until it's sorted. Just a matter of rounding everyone up and continuing the rest."

"Sounds like another day." Natasha quipped, glancing at Sherlock and giving him a difficult to read smile. "Looks like we'll have to postpone the coffee date."

Steve's blue eyes darted between the two of them but anything he was going to say was interrupted by another radio transmission.

In the end, they determined the issue had been caused by a parasite. One that had been created by genetic mutation in one of the labs, escaped, and multiplied on it's own. Dr Brianne Zamora had been the first to be infected and there'd been twenty others in total. Everyone was cleared through an MRI scan of the base of the neck, where the parasite had burrowed in those it inhabited. The parasite was extracted through a fairly simple combination of concentrated radiation and surgery.

Sherlock spent the hours after being cleared and waiting for the quarantine to be lifted, wandering the halls of the facility. He couldn't sleep. His brain was wired, even with everything that had happened. It was around one o'clock in the morning that he found himself standing in front of the large windows again. The moon was still full, the quiet early winter night brought in a rolling misty fog. And familiar footsteps met his ears and the faint smell of coffee reached his nose.

"You know, I almost expected to see you out here."

Sherlock didn't turn around. "Seems a good a place as any to think." He said, his voice low and quiet.

Natasha stopped next to him, holding out a steaming cup of coffee for him. "I brought you a coffee."

At that, Sherlock blinked down at her and took the cup with a delicate hand. She had another one in hers, the deduction was obvious. She had completely expected him to be here. Or maybe she'd _hoped_ he'd be here. He breathed in deeply. "You really did deduce I'd be out here. You're rather good."

"I know." Her lips quirked into a small smile. They both took a moment to drink the soothing warm liquid before she spoke again. "Thanks for your help today."

"I should be thanking you. You did save my life. More than once."

"Then you're most welcome." Pause. "You know, I'm considering keeping you." Natasha flexed her fingers around her own cup coffee. There was just a twitch pulling at her lips again. "Emailing for sure. Would you mind a visit sometime? I'm in London every once and a while, I'm sure we could have coffee or whatever else you want there too."

Sherlock eyed her, trying to deduce exactly what she meant. "Just coffee?"

"Maybe you could invite me on one of your cases, I'm not too picky." Natasha replied with a casual one shoulder shrug. "I like you."

Sherlock blinked a couple times, again. He found himself doing that often with her. She wasn't predictable at all. "I wouldn't…be opposed to the company." He said. "Do you like solving crimes?"

She smiled enigmatically, which was as good as a flirtation. "On occasion. I'm usually the one committing them."

"Not anymore, not maliciously at least." Sherlock said, but they both left it at that. He looked her over, calculating gaze and deductive tendency. "I'll take you."

There was a pause, but she posed the question. In time, he'd learn why she asked. "As who? Who do you want me to be?"

"Yourself." Sherlock's answer was immediate and he didn't need to do any further explanation.

* * *

When Sherlock returned to London, he was alone. But cases soon filled his schedule again, soon John was feeling better, life moved on. Along with the cases, there were emails. Conversations as well as short updates from an Avenger. He'd sent Natasha all of his tobacco ash research, which she seemed terribly excited about. He'd been quite pleased.

Months of email correspondences later Natasha met Sherlock for coffee in London. She was there for one mission of some kind. She never said exactly why, aside from it being brief but top secret. But 'just coffee' turned into a case when Sherlock's phone rang. And when Natasha Romanoff showed up on the crime scene with Sherlock, there were heads turning.

It wasn't a difficult case. In fact, it was fairly simple. Elementary. Sherlock walked into the flat, deduced the entire murder from start to finish, and then walked out ten minutes later. Natasha threw a wink over her shoulder at Lestrade and followed Sherlock out the door.

"So, that was a sight to see." She commented as they stepped out into the typical London spring afternoon. "Could watch you do that all day."

"That was a fairly easy deduction to make, judging by your smirk and dilated pupils." Sherlock stated as they walked back towards the main road for a cab.

"That easy, huh?" She paused. "If there's nothing else going on…as you said before we were interrupted. I've got a proposition for you, since I'm going to be in London for a couple days." She peeked up at his profile, hands in the pockets of her black trench coat. "Any deductions?"

Sherlock glanced down at her, his gaze calculating as he attempted to deduce what she was talking about. There were options, of course, but he couldn't quite get why she had a proposition. "Is it…a case?" He asked carefully.

Natasha laughed, the sound light and clear and not mocking. "Naturally." She quipped. "No, it's not a case. But I think it'd be a good way to stay distracted."

"Then I don't understand."

She stopped on the pavement, taking her hands out of her pockets and grabbing his coat to turn him to face her. The entire movement was graceful and smooth and it barely registered as she took him by the coat lapels and placed a surprisingly gentle kiss on his lips. She pulled away not a moment later, and opened bright green eyes to meet his. "Did that clear things up?"

"You want to…oh." Sherlock blinked a couple times, processing that as quickly as he could. That…sort of thing wasn't just something he did really ever. He'd set aside the feelings that accompanied intimate activities far away to focus on work. To focus on making his brain the best it could be without all that distraction and vulnerability. The chemistry was simple, the practical experience was limited.

Maybe it was time to reconsider his stance, if only for a curious couple days. He'd spent the day with her, saved a secret base and solved crimes and she hadn't been a distraction. His friendship with John wasn't a distraction, it was a good thing. Beneficial and practical and logical as well as sentimental and satisfactory. A friendship with a bit extra wasn't forbidden.

He could bend his own rules. If only for the weekend.

"I'm…not opposed, it's just been a _very_ long time." He answered at last. "There's nothing else on the schedule." He paused as he studied her, reaching a hesitant hand to tuck a strand of red wavy hair behind her ear. "But balance of probability says I'm going to break your heart."

"Hearts always break." She replied immediately and without sentiment. "But I'm taking a chance here." She let him go, keeping eye contact. "I like you. You're a _good_ man and I'm _so_ glad we met. I think we work well together." She offered him her hand so they could walk down the street again. "Let me show you?"

Sherlock hesitated just briefly, but slipped his hand into hers. "Alright. I accept."

Natasha smiled, and they stepped forward together.

 _"Hearts always break. And so we bend with our hearts. And we sway. But in the end… what matters is that we loved… and lived."_


End file.
